Non-congruent Alternate interior angles

This is a compass that shows an example of non-congruent alternate interior angles. Angle one is an alternate interior of angle 2 but they aren't congruent. Compasses are used in multiple industries(advertising, aerospace, metal fabrication), in order to form certain angles on blueprints and logos. I found this on the internet at:
http://www.google.com/imgres?q=geometric+compass&start=222&um=1&hl=en&client=safari&rls=en&biw=1280&bih=738&tbm=isch&tbnid=LYmNI5mjYRJZGM:&imgrefurl=http://www.technicalpens.com/index.php%3Fmain_page%3Dproduct_info%26products_id%3D393&docid=adEvon10H7olvM&imgurl=http://www.technicalpens.com/images/centro_geometry.jpg&w=1000&h=406&ei=I6uAULH1FcTG0AHV9IDICQ&zoom=1&iact=hc&vpx=449&vpy=446&dur=279&hovh=143&hovw=353&tx=180&ty=99&sig=109637316179286308971&page=8&tbnh=105&tbnw=258&ndsp=31&ved=1t:429,r:43,s:200,i:133